The KOSPI index dropped nearly 5% to 6,100 on Tuesday morning, extending a 3.7% decline from Monday. Over the past five days, the index has fallen 10.1%, though it remains up 44.89% for 2026. This downward trend follows reports of technological progress by the Chinese memory manufacturer ChangXin Memory Technologies (CXMT).
CXMT announced a new 4F² chip design that, according to TrendForce estimates, could increase memory density by 30% to 50%. The company plans to begin shipping server memory based on this design by the end of the year. This sector is a key market for South Korean giants Samsung Electronics and SK Hynix, which together account for over half of the KOSPI index by market value.
Following the news, shares of Samsung and SK Hynix each fell approximately 5% by 9:13 a.m. in Seoul. Foreign investors sold a net ₩341.4 billion in shares, while individual and institutional investors acted as buyers. In US trading, Micron shares declined 3.9%, and Sandisk shares fell 6%.
Market analysts note that CXMT currently faces challenges in stabilizing yields for high-bandwidth memory, a segment where Samsung and SK Hynix are already sampling the HBM4E generation. According to Counterpoint Research, CXMT held an 8% share of global DRAM revenue in the first quarter, trailing behind Samsung at 38%, SK Hynix at 29%, and Micron at 22%.
